Data distribution system and methods for its use

ABSTRACT

A subscriber system (10), operating in combination with other similar subscriber systems, for collectively and swiftly distributing multiple copies of digital data to a large number of other subscriber systems. The subscriber system (10) receives digital data and stores it on a storage device (38). An autonomous digital data communication subsystem (42) then obtains a copy of the digital data directly from the storage device (30) and transmits that data to another subscriber system. The autonomous digital data communication subsystem (42) includes transceivers (72, 82, 102 or 104) for exchanging digital data with ISDN communication channels (46, 44a, 44b or 44c). The transceivers (72, 82, 102 or 104) receive the digital data from a random access memory (&#34;RAM&#34;) (56) included in the autonomous digital data communication subsystem (42). A SCSI controller (52) exchanges the digital data between the RAM (56) and the storage device (38) of the subscriber system (10). A control signal processor controls the operation of the autonomous digital data communication subsystem (42) including its transceivers (72, 82, 102 and 104).

TECHNICAL FIELD

The present invention relates generally to the technical field ofelectronic data transmission, especially of compressed video data and,more particularly, to a subsystem using an Integrated Services DigitalNetwork ("ISDN") twisted pair communication channel for swiftly and costeffectively distributing digital data to a large number of subscribersystems.

BACKGROUND ART

Frequently transportation hubs such as subway platforms or trainstations, etc, or commercial businesses such as banks, etc. present avideo display to travelers or customers while the traveler or customerawaits service. Presently, these video display systems employconventional video recording technology, such as video tape or videodisk players, for storing and generating the video images presented onthe video monitors.

To keep the programs displayed on such video monitors current and tovary the programs so travelers or customers don't become bored, programsare changed frequently, even daily. Because these video display systemsemploy conventional video technology for storing and generating thevideo images, changing the program displayed on the video monitorsrequires that an individual periodically visit each site and manuallychange a video tape or disk.

U.S. Pat. No. 5,027,400, that issued Jun. 25, 1991, on an applicationfiled in the names of Toru Baji et al. ("the Baji et al. patent"),discloses a multimedia bidirectional broadcasting system thatdistributes motion picture data using a broadband ISDN communicationchannel. The system depicted in FIG. 3 of the Baji et al. patent,maintains a motion picture program data base at a "broadcasting station"for transmission over broadband ISDN communication channels in responseto requests received at the broadcasting station from subscribersystems. The subscriber system disclosed in the Baji et al. patentincludes a decoder for decoding the compressed video data and atelevision monitor for displaying the resulting images.

In addition to the broadcasting station disclosed in the Baji et al.patent, a PCT patent application entitled "Adaptive Video File Serverand Methods for Its Use," filed Feb. 11, 1992, in the names of Mark C.Koz and Masato Hata, PCT Patent Application No. PCT/US92/01084,discloses a video file server or broadcasting station that includes botha random access data storage subsystem and an archive data storagesubsystem for storing compressed video data. In response to commandsfrom subscriber systems, the video file server of this PCT patentapplication transmits compressed video data to the subscriber systemsover ISDN communication channels, or receives compressed video datatherefrom in accordance with a variety of different image datacompression standards. This first PCT patent application disclosing thevideo file server is incorporated herein by reference.

Another PCT patent application entitled "Adaptive Video SubscriberSystem and Methods for Its Use," filed Feb. 24, 1992, in the names ofMark C. Koz and Masato Hata, PCT Patent Application No. PCT/US92/01446,discloses a subscriber system that includes a communication subsystemfor receiving and transmitting compressed data via an ISDN communicationchannel. This subscriber system generates a video signal from thecompressed video data received from the ISDN communication channel toproduce a visible image on a display such as a cathode ray tube ("CRT")included in a television or red-blue-green ("RGB") monitor, a liquidcrystal display panel, a plasma panel, or any other suitable displaydevice. The subscriber system disclosed in this PCT patent applicationalso includes a SCSI controller that provides the subsystem with a SCSIport. This SCSI port permits attaching a variety of different computerperipheral devices including hard disks or an optical disk unit to thesubscriber system for storing compressed video information received fromthe ISDN communication channel. This second PCT patent applicationdisclosing the subscriber system is incorporated herein by reference.

Using the subscriber system disclosed in PCT Patent Application No.PCT/US92/01446 for generating video images displayed at transportationand commercial facilities instead of conventional video recordingtechnology permits electronically distributing, over an ISDNcommunication channel rather than manually, the program displayed atsuch remote locations. Moreover, electronic program distribution tothese subscriber systems can take place at convenient times of day suchas when there are few or no travelers or customers present, and/or whentelephone system usage is low. However, even though such a systemdistributes compressed video data, transmitting a new program from acentral location to a subscriber system over an ISDN basic accesscommunication channel requires a significant amount of time. Forexample, transmitting 10 minutes of compressed, high quality videoimages over a pair of ISDN basic rate communication channels takesapproximately one and one-half hours.

Because a major metropolitan area may include a large number of videodisplay installations whose programs must be changed frequently, evendaily, the long transmission time to distribute compressed video datadirectly to subscriber systems requires a large number of broadcastingstations or video file servers. Because of their present cost, it iseconomically impractical to dedicate a large number of broadcastingstations or video file servers to distributing video programs over ISDNbasic access communication channels when the broadcasting station orvideo file server may be in use for only a small portion of each day.

While using a communication channel having a higher data transmissionrate than an ISDN basic access communication channel, e.g., an ISDNprimary access communication channel, significantly reduces the datatransmission time and therefore, correspondingly, reduces the number ofbroadcasting stations or video file servers required to distributeprograms, the expense of such a communication channel is also beprohibitive since it will be in use for only a short interval each day.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a cost effective systemfor electronically transmitting copies of digital data to a large numberof subscriber systems in a short interval of time.

Another object of the present invention is to provide a low costsubsystem that can autonomously transmit digital data to subscribersystems.

Another object of the present invention is to provide a low costsubsystem for adapting a subscriber system to distribute digital data.

Another object of the present invention is to provide a subsystem forautonomously transmitting and/or receiving digital data.

Briefly, the present invention provides a subscriber system adapted forautonomous operation in combination with other similar subscribersystems for collectively and swiftly distributing multiple copies ofdigital data to a large number of other subscriber systems. Eachsubscriber system includes a control processor for supervising itsoverall operation including the operation of a communication, subsystem.The communication subsystem initially receives a copy of the digitaldata transmitted to the subscriber system that the subscriber systemstores into a storage device, such as a hard disk. After the digitaldata constituting a complete program of compressed video data has beenstored in the storage device, the control processor commands anautonomous digital data communication subsystem to obtain a copy of thedata directly from the storage device and to transmit the digital datato another subscriber system.

In the preferred embodiment, the autonomous digital data communicationsubsystem includes both a random access memory ("RAM"), and atransceiver that exchanges digital data with an ISDN communicationchannel. When the transceiver is transmitting digital data from theautonomous digital data communication subsystem to the ISDNcommunication channel, the transceiver receives the digital data fromthe RAM. When the transceiver is receiving digital data from the ISDNcommunication channel, the RAM receives the digital data from thetransceiver. The autonomous digital data communication subsystem alsoincludes a control signal processor for controlling its operation,including the operation of the transceiver, and of a controller meansthat exchanges digital data between the RAM and the storage device ofthe subscriber system.

These and other features, objects and advantages will be understood orapparent to those of ordinary skill in the art from the followingdetailed description of the preferred embodiment as illustrated in thevarious drawing figures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram depicting a subscriber system in accordancewith the present invention including a storage device and plurality ofautonomous digital data communication subsystems; and

FIG. 2 is a block diagram of the autonomous digital data communicationsubsystem depicted in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 depicts a subscriber system referred to by the general referencecharacter 10 in accordance with the present invention. The subscribersystem 10 is preferably of the type described in PCT Patent ApplicationNo. PCT/US92/01446 entitled "Adaptive Video Subscriber System andMethods for Its Use," filed Feb. 24, 1992, in the names of Mark C. Kozand Masato Hata, that is incorporated herein by reference.

The preferred subscriber system 10 supplies video signals to a cathoderay tube ("CRT") 12 for producing a visible image on the CRT 82,particularly in publicly accessible places such as subway platforms,train station, or commercial businesses. The video signals may besupplied as red-green-blue ("RGB") video signals via a RGB bus 14directly to the CRT 12 included in an RGB monitor. The subscriber system10 may also supply the video signals to the CRT 12 as a NationalTelevision Systems Committee ("NTSC") color composite video signal via acomposite video signal output line 16. Alternatively, the subscribersystem 10 may supply video signals to the CRT 12 via a chroma outputline 22 and a luminance output line 24 of a video output signal bus 26.The subscriber system 10 also provides audio signals via an audioline-out jack 28.

The subscriber system 10 includes a communication subsystem, that is notseparately illustrated in FIG. 1 but is described in PCT PatentApplication No. PCT/US92/01446, for receiving compressed video signalsin the form of digital data over a communication channel such as an ISDNcommunication channel 32. The ISDN communication channel 32 of thesubscriber system 10 may be either an ISDN primary access communicationchannel or an ISDN basic access communication channel.

The subscriber system 10 also includes a port 34 for a Small ComputerSystem Interface-2 ("SCSI-2") bus 36 for exchanging commands and dataamong a variety of different computer peripheral devices such as hardand/or floppy disks, a Digital Audio Tape ("DAT"), a CD-ROM drive, anoptical disk unit, a printer, a scanner, a plotter, etc. Operating underthe supervision of a control processor included in the subscriber system10 that is not separately illustrated in FIG. 1 but is described in PCTPatent Application No. PCT/US92/01446, the subscriber system 10 maytransfer compressed video signals, that it receives in the form ofdigital data, from the ISDN communication channel 32 to the SCSI-2 bus36 for storage in a storage device 38, such as a hard disk or an opticaldisk unit.

In accordance with the present invention, the subscriber system 10includes a plurality of autonomous digital data communication subsystems42 that also connect to the SCSI-2 bus 36. Each autonomous digital datacommunication subsystem 42 operates under the supervision of the controlprocessor included in the subscriber system 10. When the subscribersystem 10 is operating autonomously for swiftly distributing multiplecopies of digital data to a large number of other subscriber systems,under the supervision of the control processor each digital datacommunication subsystem 42 autonomously obtains a copy of the digitaldata directly from the storage device 38 via the SCSI-2 bus 36. Aftereach autonomous digital data communication subsystem 42 obtains thedigital data from the storage device 38, it transmits the digital datato other subscriber systems via ISDN communication channels such as ISDNbasic access communication channels 44a, 44b and 44c, and/or an ISDNprimary access communication channel 46 illustrated in FIG. 1.

FIG. 2 is a block diagram depicting the autonomous digital datacommunication subsystem 42 of FIG. 1. The autonomous digital datacommunication subsystem 42 includes a SCSI controller 52 that mayexchange both commands and digital data directly with the storage device38 via the SCSI-2 bus 36. The SCSI controller 52 preferably is a MB86603SCSI-2 protocol controller manufactured by Fujitsu VLSI Inc. Afterreceiving digital data from the SCSI bus 36, the SCSI controller 52transmits that data over an address and data bus 54 for temporarystorage in a random access memory ("RAM") 56. The RAM 56 preferablyincludes 256 kilobytes of static RAM, one-half of which is used forprogram storage and the other half of which is used for data storage.

In addition to the RAM 56, the autonomous digital data communicationsubsystem 42 also includes a "boot" read only memory ("ROM") 62. The ROM62 stores a computer program that is fetched and executed via theaddress and data bus 54 by a control signal processor 64. The ROM 62preferably stores 256 kilobytes of computer program for execution by thecontrol signal processor 64. The control signal processor 64 ispreferably a TMS320C25 digital signal processor Integrated Circuit("IC") that is more completely described in the "Texas Instrument DSPHandbook" and is manufactured by Texas Instruments Incorporated ofDallas, Tex. Responsive to the supervision of the control processor forthe subscriber system 10, the computer program executed by the controlsignal processor 64 controls the overall operation of the autonomousdigital data communication subsystem 42.

To effect the overall operation of the autonomous digital datacommunication subsystem 42 in transmitting digital data received fromthe SCSI-2 bus 36 to the ISDN basic access communication channels 44aand to the ISDN primary access communication channel 46, the controlsignal processor 64 transmits control signals via the address and databus 54 to a first serial controller 66, and to a Programmable ArrayLogic Integrated Circuit ("PAL") 68. The first serial controller 66 ispreferably an AM82525 Serial Controller manufactured both by SiemensIntegrated Circuit Division of Santa Clara, Calif. The PAL 68 ispreferably a MACH 110 manufactured by Advanced Micro Devices Inc. ofSunnyvale, Calif..

The PAL 68 exchanges control and data signals with a primary ratetransceiver 72 via an ISDN primary rate data bus 74. The primary ratetransceiver 72 is preferably a Dallas Semiconductor DS2280 T1 Line CardStik™. The Dallas DS2280, more completely described in a "DallasSemiconductor Handbook," is manufactured by Dallas Semiconductor ofDallas, Tex. The PAL 68 adapts signals on the address and data bus 54and the primary rate bus 74 so the primary rate transceiver 72 mayexchange signals with other ICs such as the control signal processor 64and the RAM 56. Operating under the control of the computer programexecuted by the control signal processor 64, the primary ratetransceiver 72 may either receive digital data from or transmit digitaldata to the ISDN primary access communication channel 46. Whentransmitting digital data to the ISDN primary access communicationchannel 46, the primary rate transceiver 72 receives the digital datafrom the RAM 56 via the address and data bus 54, the PAL 68 and theprimary rate bus 74. When receiving digital data from the ISDN primaryaccess communication channel 46, the primary rate transceiver 72transmits serial data to the control signal processor 64, to the firstserial controller 66, and to the PAL 68 via a PCM bus 76.

In addition to receiving serial data from the primary rate transceiver72 via the PCM bus 76, the first serial controller 66 also receivesserial data from a basic rate transceiver 82 over a multiplexed serialbus 84. The basic rate transceiver 82, which also connects to theaddress and data bus 54, operates under the control of the controlsignal processor 64 for exchanging digital data with the ISDN basicaccess communication channel 44a. When the first basic rate transceiver82 transmits digital data to the ISDN basic access communication channel44a, it receives the data directly from the RAM 56 via the address anddata bus 54. When the first basic rate transceiver 82 receives digitaldata from the ISDN basic access communication channel 44a, it transmitsserial data to the first serial controller 66 via the first multiplexedserial bus 84. The first serial controller 66 receives serial data fromthe primary rate transceiver 72 and/or from the first basic ratetransceiver 82, organizes it into 16 bit words, and stores those wordsdirectly into the RAM 56 via the address and data bus 54.

As described thus far, the autonomous digital data communicationsubsystem 42 is capable of exchanging digital data with either the ISDNbasic access communication channel 44a or with the ISDN primary accesscommunication channel 46; or simultaneously with both the channels 44aand 46. However, the preferred embodiment of the autonomous digital datacommunication subsystem 42 may also incorporate an optional "daughterboard" 92, that is depicted within a dashed line in FIG. 2. The daughterboard 92 includes a second serial controller 94, that is preferably anAM82525 Serial Controller of the type characterized more completelyabove. The second serial controller 94 connects to the address and databus 54, and to a daughter board bus 96. The daughter board bus 96interconnects the second serial controller 94 with the PAL 68, and withboth a second basic rate transceiver 102 and a third basic ratetransceiver 104. The basic rate transceivers 102 both connect to theaddress and data bus 54, and respectively to a second multiplexed serialbus 106 and a third multiplexed serial bus 108 that respectivelyinterconnect the basic rate transceivers 102 and 104 with the secondserial controller 94. Both the second serial controller 94 and the basicrate transceivers 102 and 104 receive control signals from the PAL 68via the daughter board bus 96.

Similar to the first basic rate transceiver 82, the second and thirdbasic rate transceivers 102 and 104 operate under the control of thecontrol signal processor 64 for exchanging digital data respectivelywith the ISDN basic access communication channels 44b and 44c. When thebasic rate transceivers 102 and 104 respectively transmit digital datato the ISDN basic access communication channel 44a, they receive thedata directly from the RAM 56 via the address and data bus 54. When thebasic rate transceivers 102 and 104 receive digital data from the ISDNbasic access communication channel 44a, they respectively transmitsserial data to the second serial controller 94 via the first multiplexedserial bus 84. Similar to the first serial controller 66, the secondserial controller 94 receives serial data from the basic ratetransceivers 102 and/or 104, organizes it into 16 bit words, and storesthose words directly into the RAM 56 via the address and data bus 54.

Digital Data Distribution

The subscriber system 10 described above is particularly useful fordistributing multiple copies of digital data to a large number of othersubscriber systems in the following way. A broadcasting station, such asthat described in the Baji et al. patent, or a video file server, suchas that described in PCT patent application PCT/US92/01084, transmits aprogram consisting of compressed, high quality video images first to asingle subscriber system 10 over a pair of ISDN basic accesscommunication channels. As the subscriber system 10 receives thisdigital data, the data is transmitted over the SCSI-2 bus 36 for storageon the storage device 38. After approximately one and one-half hours,the subscriber system 10 will store on the storage device 38approximately 10 minutes of program for repeated presentation on its CRT12.

However, in addition to displaying the program now stored on the storagedevice 38 on the CRT 12, the control processor of the subscriber system10 orders each of the autonomous digital data communication subsystems42 to begin autonomously obtaining a copy of the digital data from thestorage device 38 and transmitting that digital data to other subscribersystems. In ordering each autonomous digital data communicationsubsystem 42 to obtain and transmit the digital data, the controlprocessor of the subscriber system 10 may provide each communicationsubsystem 42 with data specifying the telephone numbers of othersubscriber systems to which the digital data will be transmitted, orsuch dialing information could be included in the data which thecommunication subsystem 42 obtains from the storage device 38.

Upon being ordered to obtain a copy of the digital data from the storagedevice 38, the control signal processor 64 in the autonomous digitaldata communication subsystem 42 commands the SCSI controller 52 to beginobtaining the digital data directly from the storage device 38 via theirshared SCSI-2 bus 36. As the SCSI controller 52 receives the digitaldata from the storage device 38, it stores the data directly into theRAM 56 that is shared among all the transceivers 72, 82, 102 and 104.Thereafter, under the control of the control signal processor 64, thedigital data is transferred over the address and data bus 54 to anycombination of the transceivers 72, 82, 102 and 104 for transmission toother subscriber systems respectively over the ISDN communicationchannels 46, 44a, 44b and/or 44c.

While the subscriber system 10 illustrated in FIG. 1 includes only fourautonomous digital data communication subsystems 42, each subscribersystem 10 may practically include at least eight communicationsubsystems 42, and could actually include as many as fourteencommunication subsystems 42. Thus, for example, if eight autonomousdigital data communication subsystems 42 were included in the subscribersystem 10, and if each such communication subsystem 42 were to transmitthe digital data to other subscriber systems only over its three ISDNbasic access communication channels 44a, 44b and 44c, approximatelythree hours after the broadcasting station or video file server begantransmitting the compressed video data to the subscriber system 10, thesingle digital data initially transmitted to only the subscriber system10 is now distributed to at least twenty-five subscriber systems, i.e.,the original subscriber system 10 plus twenty-four other subscribersystems (three subscriber systems for each of the eight autonomousdigital data communication subsystems 42).

Repeating the process described above once again only this time witheach of the twenty-five subscriber systems that now have copies of theprogram stored on their storage devices 38 transmitting the digital datato another twenty-four subscribers distributes the program to anadditional six-hundred subscriber systems within approximately four andone-half hours after the broadcasting station or video file server firstbegan transmitting the compressed video data to the first subscribersystem 10. A third iteration of this process with each of thesix-hundred and twenty-five subscriber systems transmitting the digitaldata to twenty-four other subscriber systems distributes the program toas many as 15,625 subscriber systems within approximately six hoursafter the broadcasting station or video file server first begantransmitting the compressed video data to the first subscriber system10.

Thus, the addition of autonomous digital data communication subsystems42 into the subscriber system 10 disclosed in PCT patent applicationPCT/US92/01446 permits the distribution of multiple copies of digitaldata to a large number of subscriber systems within a practical amountof time, e.g. approximately six hours. Moreover, the preceding exampleof the distribution of the same digital data to 15,625 subscribersystems within approximately six hours illustrates only a fraction ofthe capability of subscriber systems, such as the subscriber system 10disclosed herein, to collectively distribute digital data using theautonomous digital data communication subsystem 42.

The capability of each subscriber system 10 to distribute digital datacan be modestly increased by also transmitting a copy of the data overthe ISDN communication channel 32 included in each subscriber system 10.If the ISDN communication channel 32 of each subscriber system 10 werealso used for distributing the digital data, after approximately sixhours the digital data would be distributed to 17,576 rather than toonly 15,625 subscriber systems. It is readily apparent that using anISDN primary access communication channel 46 to distribute the digitaldata would even more markedly increase the speed of data distribution.

However, an even more dramatic increase in the capability fordistributing digital data can be obtained if the subscriber system 10orders each of the autonomous digital data communication subsystems 42to begin autonomously obtaining a copy of the digital data andtransmitting it while the subscriber system 10 is still receiving thedata and before it has stored all of the data on the storage device 38.If the subscriber system 10 were to order its autonomous digital datacommunication subsystems 42 to commence distributing the digital dataafter receiving only one-sixth of the data, then the data could bedistributed to 15,625 subscriber systems in only one and one-half of thetime required to transmit the data from the broadcasting station orvideo file server to the first subscriber system 10. In the example setforth above, rather than taking approximately six hours to distributethe digital data to 15,625 subscriber systems, by beginning todistribute the data after receiving only one-sixth of it all 15,625subscriber systems will complete their reception of the data inapproximately two and one-quarter hours. Alternatively, after six hoursof such progressive distribution, the digital data could be distributedto 25¹⁸ subscriber systems, a number of subscriber systems so large asto be far beyond any possible practical realization.

Industrial Applicability

While thus far the utility of the autonomous digital data communicationsubsystem 42 has been described in the context of swiftly distributingmultiple copies of compressed video data to a large number of subscribersystems, the autonomous digital data communication subsystem 42 may alsobe effectively applied in distributing copies of different digital datato a large number of subscriber systems. Since the autonomous digitaldata communication subsystem 42 exchanges digital data with the SCSI-2bus 36, it can be used with any digital computer system that provides aSCSI-2 bus. If, for example, a database were maintained on such acomputer and only selected portions of the database need be distributedto specified remote sites, then each of the autonomous digital datacommunication subsystems 42 could be ordered to transmit only selectedportions of the database to up to eight remote sites. For example, ifthe centralized database maintained an inventory of items in stock atvarious company locations, then the autonomous digital datacommunication subsystems 42 could be effectively used in providing localinventory information to each individual company location.

Similarly, while the autonomous digital data communication subsystem 42has been described thus far in the context of distributing digital datato a large number of subscriber systems, it could also be effectivelyemployed for autonomously collecting data from a large number ofdifferent locations, and storing such data into a database on thestorage device 38. After the data received by the transceivers 72, 82,102 and/or 104 has been stored in the RAM 56 as described above, thecontrol signal processor 64 of the autonomous digital data communicationsubsystem 42 may order the SCSI controller 52 to store the data into thestorage device 38 via the SCSI-2 bus 36.

Although the present invention has been described in terms of thepresently preferred embodiment, it is to be understood that suchdisclosure is purely illustrative and is not to be interpreted aslimiting. Consequently, without departing from the spirit and scope ofthe invention, various alterations, modifications, and/or alternativeapplications of the invention will, no doubt, be suggested to thoseskilled in the art after having read the preceding disclosure.Accordingly, it is intended that the following claims be interpreted asencompassing all alterations, modifications, or alternative applicationsas fall within the true spirit and scope of the invention.

What is claimed is:
 1. A subscriber system adapted for autonomousoperation in combination with other similar subscriber systems forcollectively and swiftly distributing multiple copies of digital datarespectively to a large number of other subscriber systems, eachsubscriber system comprising:a control processor for controlling overalloperation of said subscriber system; a communication subsystem operatingunder the supervision of said control processor for receiving a copy ofthe digital data transmitted to said subscriber system; a storage deviceoperating under the supervision of said control processor for storingthe copy of the digital data received by said communication subsystem;and an autonomous digital data communication subsystem operating underthe supervision of said control processor for autonomously obtaining acopy of the digital data directly from said storage device andtransmitting the digital data to another subscriber system.
 2. Thesubscriber system of claim 1 wherein said autonomous digital datacommunication subsystem concurrently transmits a copy of the data toseveral different subscriber systems.
 3. The subscriber system of claim1 adapted for individually transmitting multiple copies of digital datarespectively to a large number of other subscriber systems, saidsubscriber system further comprising:a plurality of autonomous digitaldata communication subsystems, each autonomous digital datacommunication subsystem operating under the supervision of said controlprocessor for autonomously obtaining a copy of the digital data directlyfrom said storage device and transmitting the digital data to anothersubscriber system, all of said autonomous digital data communicationsubsystems included in said subscriber system concurrently obtaining andtransmitting the digital data, whereby said autonomous digital datacommunication subsystems concurrently transmit the digital data to aplurality of other subscriber systems.
 4. The subscriber system of claim3 wherein each autonomous digital data communication subsystemconcurrently transmits a copy of the data to several differentsubscriber systems.
 5. The subscriber system of claim 1 wherein eachautonomous digital data communication subsystem comprises:a transceiverfor exchanging digital data with an ISDN communication channel; a randomaccess memory ("RAM") from which said transceiver receives digital datawhen said transceiver is transmitting such data to an ISDN communicationchannel, or which receives digital data from said transceiver when saidtransceiver is receiving such data from an ISDN communication channel; acontrol signal processor for controlling the operation of saidautonomous digital data communication subsystem including saidtransceiver; and controller means, operating under the control of saidcontrol signal processor, for exchanging digital data between said RAMand said storage device.
 6. The subscriber system of claim 5 whereinsaid autonomous digital data communication subsystem is adapted forconcurrently exchanging digital data with a plurality of remotelocations, said autonomous digital data communication subsystemcomprising:a plurality of transceivers, each transceiver autonomouslyexchanging digital data with an ISDN communication channel, eachtransceiver when transmitting digital data to an ISDN communicationchannel autonomously fetching such data from the RAM, and eachtransceiver when receiving digital data from an ISDN communicationchannel autonomously storing such data into the RAM.
 7. The subscribersystem of claim 6 wherein at least one of said transceivers of saidautonomous digital data communication subsystem exchanges digital datawith a basic access ISDN communication channel and another of saidtransceivers exchanges digital data with a primary access ISDNcommunication channel.
 8. The subscriber system of claim 6 wherein saidcontroller means of said autonomous digital data communication subsystemexchanges both commands and digital data directly with said storagedevice via a shared bus.
 9. The subscriber system of claim 6 wherein thedigital data is compressed video data, said subscriber system furthercomprises a visual display means for presenting an image of the digitaldata.
 10. The subscriber system of claim 1 wherein said autonomousdigital data communication subsystem comprises:a transceiver forexchanging digital data with an ISDN communication channel; a randomaccess memory ("RAM") from which said transceiver receives digital datawhen said transceiver is transmitting such data to an ISDN communicationchannel, or which receives digital data from said transceiver when saidtransceiver is receiving such data from an ISDN communication channel; acontrol signal processor for controlling the operation of saidautonomous digital data communication subsystem including saidtransceiver; and controller means, operating under the control of saidcontrol signal processor, for exchanging digital data between said RAMand said storage device.
 11. The subscriber system of claim 10 whereinsaid autonomous digital data communication subsystem is adapted forconcurrently exchanging digital data with a plurality of remotelocations, said autonomous digital data communication subsystemcomprising:a plurality of transceivers, each transceiver autonomouslyexchanging digital data with an ISDN communication channel, eachtransceiver when transmitting digital data to an ISDN communicationchannel autonomously fetching such data from the RAM, and eachtransceiver when receiving digital data from an ISDN communicationchannel autonomously storing such data into the RAM.
 12. The subscribersystem of claim 11 wherein at least one of said transceivers of saidautonomous digital data communication subsystem exchanges digital datawith a basic access ISDN communication channel and another of saidtransceivers exchanges digital data with a primary access ISDNcommunication channel.
 13. The subscriber system of claim 11 whereinsaid controller means of said autonomous digital data communicationsubsystem exchanges both commands and digital data directly with saidstorage device via a shared bus.
 14. The subscriber system of claim 11wherein the digital data is compressed video data, said subscribersystem further comprises a visual display means for presenting an imageof the digital data.
 15. The subscriber system of claim 1 wherein thedigital data is compressed video data, said subscriber system furthercomprises a visual display means for presenting an image of the digitaldata.
 16. An autonomous digital data communication subsystem forconcurrently exchanging digital data with a plurality of remotelocations, said autonomous digital data communication subsystemcomprising:a plurality of transceivers, each transceiver autonomouslyexchanging digital data with an ISDN communication channel; a RAM fromwhich each transceiver autonomously receives digital data when saidtransceiver is transmitting such data to an ISDN communication channel,or which receives digital data from each transceiver autonomously whensaid transceiver is receiving such data from an ISDN communicationchannel; a control signal processor for controlling the operation ofsaid autonomous digital data communication subsystem including saidtransceivers; and controller means, operating under the control of saidcontrol signal processor, for exchanging digital data between said RAMand a storage device.
 17. The autonomous digital data communicationsubsystem of claim 16 wherein at least one of the transceivers exchangesdigital data with a basic access ISDN communication channel and anotherof the transceivers exchanges digital data with a primary access ISDNcommunication channel.
 18. The autonomous digital data communicationsubsystem of claim 16 wherein said controller means exchanges bothcommands and digital data directly with the storage device via a sharedbus.
 19. The autonomous digital data communication subsystem of claim 16wherein said controller means exchanges both commands and digital datadirectly with the storage device via a shared bus.